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Commit a193a4ab authored by Patrick McHardy's avatar Patrick McHardy Committed by David S. Miller
Browse files

[NETFILTER]: Fix skb->nf_bridge lifetime issues 



The bridge netfilter code simulates the NF_IP_PRE_ROUTING hook and skips
the real hook by registering with high priority and returning NF_STOP if
skb->nf_bridge is present and the BRNF_NF_BRIDGE_PREROUTING flag is not
set. The flag is only set during the simulated hook.

Because skb->nf_bridge is only freed when the packet is destroyed, the
packet will not only skip the first invocation of NF_IP_PRE_ROUTING, but
in the case of tunnel devices on top of the bridge also all further ones.
Forwarded packets from a bridge encapsulated by a tunnel device and sent
as locally outgoing packet will also still have the incorrect bridge
information from the input path attached.

We already have nf_reset calls on all RX/TX paths of tunnel devices,
so simply reset the nf_bridge field there too. As an added bonus,
the bridge information for locally delivered packets is now also freed
when the packet is queued to a socket.

Signed-off-by: default avatarPatrick McHardy <kaber@trash.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 6ffd30fb

include/linux/skbuff.h

+14 −10
Original line number Diff line number Diff line
@@ -1351,16 +1351,6 @@ static inline void nf_conntrack_put_reasm(struct sk_buff *skb) 
		kfree_skb(skb);

}

#endif

static inline void nf_reset(struct sk_buff *skb)

{

	nf_conntrack_put(skb->nfct);

	skb->nfct = NULL;

#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)

	nf_conntrack_put_reasm(skb->nfct_reasm);

	skb->nfct_reasm = NULL;

#endif

}



#ifdef CONFIG_BRIDGE_NETFILTER

static inline void nf_bridge_put(struct nf_bridge_info *nf_bridge)

{
@@ -1373,6 +1363,20 @@ static inline void nf_bridge_get(struct nf_bridge_info *nf_bridge) 
		atomic_inc(&nf_bridge->use);

}

#endif /* CONFIG_BRIDGE_NETFILTER */

static inline void nf_reset(struct sk_buff *skb)

{

	nf_conntrack_put(skb->nfct);

	skb->nfct = NULL;

#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)

	nf_conntrack_put_reasm(skb->nfct_reasm);

	skb->nfct_reasm = NULL;

#endif

#ifdef CONFIG_BRIDGE_NETFILTER

	nf_bridge_put(skb->nf_bridge);

	skb->nf_bridge = NULL;

#endif

}



#else /* CONFIG_NETFILTER */

static inline void nf_reset(struct sk_buff *skb) {}

#endif /* CONFIG_NETFILTER */

net/ipv4/netfilter/ipt_REJECT.c

+0 −4
Original line number Diff line number Diff line
@@ -154,10 +154,6 @@ static void send_reset(struct sk_buff *oldskb, int hook) 
	/* This packet will not be the same as the other: clear nf fields */

	nf_reset(nskb);

	nskb->nfmark = 0;

#ifdef CONFIG_BRIDGE_NETFILTER

	nf_bridge_put(nskb->nf_bridge);

	nskb->nf_bridge = NULL;

#endif



	tcph = (struct tcphdr *)((u_int32_t*)nskb->nh.iph + nskb->nh.iph->ihl);